CRC-CCITT für JAVA

public class Crc_CCITT //xModem

{

    long act_CRC_ul;

    // String [] test = new String[] {"E0", "06", "52"}; //--> Soll CRC = 7020  / ist= 5e97                       XX

     String[] test = new String[] {"E0", "06", "52", "53"}; //--> Soll CRC = 3401 / ist= 3401                     OK

    // String [] test = new String[] {"E0", "06", "52", "53", "44"}; //--> Soll CRC = 7F97 / ist= 1878            XX

    // String [] test = new String[] {"E0", "06", "52", "53", "44", "E7"}; //--> Soll CRC = 95B1 / ist= 95B1      OK

    public Crc_CCITT()

    {

        calcCRC(makeIntArray());

        System.out.println(Long.toHexString(act_CRC_ul & 0xFFFF));

    }

    public static void main(String[] args)

    {

        Crc_CCITT crc= new Crc_CCITT();                 

    }

    private int[] makeIntArray()//rechnet die Strings in Int-werte um.

    {

        int[] zeichen = new int[test.length];

        for (int n = 0; n < test.length; n++)

        {

            zeichen[n] = Integer.parseInt(test[n], 16);

        }

        return zeichen;

    }

    private void calcCRC(int[] msg)

    {

        int u;

        int msb_c, lsb_c;

        //

        act_CRC_ul = 0L;

        // erste 2 Bytes MSB und LSB invertiert:

        msb_c = msg[0];

        lsb_c = msg[1];

        msg_upd2crc(msb_c, lsb_c);

        // rest der MSG: 

        for (u = 2; u < msg.length; u++)

        {

            lsb_c = msg[u];

            u++;

            if (u == msg.length)

            {

                msb_c = 0; // when message length is odd

            }

            else

            {

                msb_c = msg[u];

            }

            msg_upd2crc(lsb_c, msb_c);

        }

        msg_upd2crc(0, 0);

    }

    public void msg_upd2crc(int msb_c, int lsb_c)

    {

        long shifter_w, data_w;

        long carry_w;

        shifter_w = 0x8000L;

        data_w = (((msb_c << 8) & 0xff00L) | (lsb_c & 0x00ffL));

        do

        {

            carry_w = act_CRC_ul & 0x8000L;

            act_CRC_ul <<= 1;

            if ((data_w & shifter_w) != 0L)

            {

                act_CRC_ul++;

            }

            if (carry_w != 0L)

            {

                act_CRC_ul ^= 0x1021L;

            }

            shifter_w >>= 1;

            act_CRC_ul &= 0xFFFFFF;

        }

        while (shifter_w != 0L);

    }     

}